Subject: Re: Bug/regression report - 'git stash push -u' fatal errors when sub-repo present

From: Junio C Hamano <[email-masked]>
Date: Thu, 30 Sep 2021 09:35:36 -0700

René Scharfe <[email-masked]> writes:

> Looping in Stolee as the author of 6e773527b6 (sparse-index: convert
> from full to sparse, 2021-03-30).
>
> Here's a raw patch for that.  Versions before 6e773527b6 pass the
> included test.
>
> The magic return value of 2 is a bit ugly, but allows adding the
> additional check only to the call-site relevant to the bug report.
>
> I don't know if other callers of verify_path() might also need that
> check, or if it is too narrow.

The callers inside read-cache.c, which I think were the original
intended audiences of the function, always call verify_path() with
the pathname suitable to be stored as a cache entry.

The callee never has to assume an extra trailing slash might exist
at the end.  And verify_path() said "no", if any caller passed an
extra trailing slash before the commit in question.

I _think_ we defined the new "tree" type entries the sparse index
stuff added to be the _only_ cache entries whose path always ends
with a slash?  If so, perhaps we should audit the existing callers 
and move the "paths that come from end-users to be entered to the
index must never end with a slash" sanity check this function gave
us, which was broken by 6e773527b6, perhaps?

"git update-index" should never allow to create a "tree" kind of
cache entry (making it sparse again should be the task of systems
internal, and should not be done by end-user feeding a pre-shrunk
"tree" kind of entry to record a sparsely populated state, if I
understand correctly), so its call to verify_path(), if it ends with
a directory separator, should say "that's not a good path".

Prehaps we can rename verify_path() to verify_path_internal() that
is _known_ to be called with names that are already vetted to be
stored in ce_name and convert callers inside read-cache.c to call
it, and write verify_path() as a thin wrapper of it to fail when the
former stops by returning S_ISDIR() at the place your fix touched,
or something?

Thanks.

>
> René
>
>
> ---
>  builtin/update-index.c             | 15 ++++++++++++++-
>  read-cache.c                       |  2 +-
>  t/t3905-stash-include-untracked.sh |  6 ++++++
>  3 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/builtin/update-index.c b/builtin/update-index.c
> index 187203e8bb..3d32db7304 100644
> --- a/builtin/update-index.c
> +++ b/builtin/update-index.c
> @@ -445,10 +445,22 @@ static void chmod_path(char flip, const char *path)
>  	die("git update-index: cannot chmod %cx '%s'", flip, path);
>  }
>
> +static int is_nonbare_repo_dir(const char *path)
> +{
> +	int ret;
> +	struct strbuf sb = STRBUF_INIT;
> +
> +	strbuf_addstr(&sb, path);
> +	ret = is_nonbare_repository_dir(&sb);
> +	strbuf_release(&sb);
> +	return ret;
> +}
> +
>  static void update_one(const char *path)
>  {
>  	int stat_errno = 0;
>  	struct stat st;
> +	int ret;
>
>  	if (mark_valid_only || mark_skip_worktree_only || force_remove ||
>  	    mark_fsmonitor_only)
> @@ -458,7 +470,8 @@ static void update_one(const char *path)
>  		stat_errno = errno;
>  	} /* else stat is valid */
>
> -	if (!verify_path(path, st.st_mode)) {
> +	ret = verify_path(path, st.st_mode);
> +	if (ret == 0 || (ret == 2 && is_nonbare_repo_dir(path))) {
>  		fprintf(stderr, "Ignoring path %s\n", path);
>  		return;
>  	}
> diff --git a/read-cache.c b/read-cache.c
> index f5d4385c40..0188b5b798 100644
> --- a/read-cache.c
> +++ b/read-cache.c
> @@ -1040,7 +1040,7 @@ int verify_path(const char *path, unsigned mode)
>  			 * sparse directory entries.
>  			 */
>  			if (c == '\0')
> -				return S_ISDIR(mode);
> +				return S_ISDIR(mode) ? 2 : 0;
>  		} else if (c == '\\' && protect_ntfs) {
>  			if (is_ntfs_dotgit(path))
>  				return 0;
> diff --git a/t/t3905-stash-include-untracked.sh b/t/t3905-stash-include-untracked.sh
> index dd2cdcc114..5390eec4e3 100755
> --- a/t/t3905-stash-include-untracked.sh
> +++ b/t/t3905-stash-include-untracked.sh
> @@ -422,4 +422,10 @@ test_expect_success 'stash show --{include,only}-untracked on stashes without un
>  	test_must_be_empty actual
>  '
>
> +test_expect_success 'stash -u ignores sub-repository' '
> +	test_when_finished "rm -rf sub-repo" &&
> +	git init sub-repo &&
> +	git stash -u
> +'
> +
>  test_done
> --
> 2.33.0